It is a decent sizer set that has sizes from .675? Up to .690? So you will always be able to find a sizer that will fit the paint.

I like my ccm barrel kit. But I like freaks more... So if you already have a barrel kit that you like then the ccm one might be necessary. If you don't have a kit already then the ccm kit will work on any AC threaded gun.

If you plan on keeping your gun the this wont matter but if you eventually want to sell the gun. Having the kit adds a bit of value.

Not really worth it in my opinion. I'd put money on you only using 2, maybe 3 over the life of it. I have a barrel kit and regret it. Empire nailed it with the quantity and sizes IMO (.675, .680, .685).